ENHANCING THE AQUACULTURE POTENTIAL AND STOCKING OF WALLEYE (SANDER VITREUS) THROUGH MANAGEMENT OF FEED NUTRITION

Abstract

Walleye (Sander vitreus) is an ecologically important and highly prized food fish in the Midwest region. With increasing commercial harvesting of wild walleye, more walleye are being stocked into the Great Lakes through aquaculture conservation and raised for production in aquaculture businesses. For aquaculture businesses and conservation, the feed can cost more than 50% of the entire operation’s total costs. Developing a profitable walleye aquaculture industry is crucial to meet the ever-growing market demand. This study aims to establish a cost-effective feeding strategy and formulate a nutritionally balanced feed to enhance walleye aquaculture. Two feeding trials were conducted on walleye with an initial body weight of 37 ± 1 g (n=30) within a flow-through water system (21 – 23 °C). In the first trial, walleye were subjected to four feeding rates (0.8%, 1.6%, 2.4%, and 4.0% of body weight per day) for 6 weeks to determine the optimal feeding rate (OFR). The feed was a commercial diet, consisting of 42% protein, 16% lipids, and 13.6% starch. The second feeding trial lasted for 9 weeks and aimed to assess the response of walleye to various diets formulated with different lipid-to-starch ratios: 0.50, 0.65, 0.83, 1.06, and 1.36. The dietary lipids ranged between 11% to 19%, while the dietary starch levels ranged between 14% to 22%. The protein content was consistent across all diets at 46.6%. Each treatment consisted of three replicates with 20 fish per replication. The walleye were fed four times daily (9:00 a.m., 12:00 p.m., 3:00 p.m., and 6:00 p.m.) using automatic feeders. At the end of each feeding trial, samples for both growth data and proximate composition were taken. The fish were subjected to acuate hypoxia (